Mentolabial angle

What the mentolabial angle is

The mentolabial angle describes the soft-tissue fold between your lower lip and your chin, known anatomically as the labiomental sulcus. In profile it appears as the gentle valley where the lip region gives way to the chin. The metric reads the angle of that fold: a larger angle means a shallower, flatter transition, while a smaller angle means a deeper, more pronounced crease.

This fold sits at the boundary between soft tissue and the underlying bone of the chin, so its depth reflects two things at once, the fullness and posture of the lower lip and the forward position of the chin behind it. That is why it is read in profile rather than from the front.

Why the fold matters to the profile

A fold that is defined but not deep gives the lower face a pleasing, finished contour, whereas a sulcus that is almost flat or unusually deep tends to stand out. The clinical profile tradition, including Naini 2011 and Arnett & Bergman 1993, treats the labiomental fold as a marker of how the lips and chin relate, because a very deep fold can accompany a strong or over-set chin and a flat one can accompany a recessed chin.

As with every measure on this site, this is an aesthetic convention rather than an objective rule, and norms differ by sex and by population. A value outside the preferred range simply describes a shape; it says nothing about a person's worth.

The typical range, and why it is so high

This tool scores a band of roughly 150 to 172 degrees, with a modelled mean near 162 degrees. That is noticeably higher than the soft-tissue norms in the clinical literature, which run around 120 to 135 degrees and are often cited near 129 degrees in men and 134 degrees in women.

The gap is purely methodological. The face mesh measures to the menton, the lowest point of the chin, rather than to a soft-tissue tangent of the kind a clinician would use, so it reads about thirty degrees higher across the board. The band has been shifted onto that scale, which is why the numbers here look larger than a textbook would suggest. Compare your value to this band, not to the clinical figures.

Interpreting your own number

The labiomental fold is sensitive to lip posture: clenching the lips, holding a slight smile or straining the chin muscles all change its depth. For a meaningful reading, use a relaxed, neutral side photo with the lips lightly together, and check whether a second photo gives a similar value before drawing any conclusion.

What is changeable and what is fixed

Some of what you see in this fold is expression and posture, which you can change at no cost simply by relaxing the lower face. The deeper driver, the forward position and prominence of the chin, is bone structure and does not move with grooming or exercise.

Filler can soften a deep fold temporarily, and a genioplasty reshapes the chin and the fold permanently. Both are described here only as factual options. Either is a clinical decision with trade-offs and is best discussed with a qualified practitioner.